Incline devices for elevating the head and upper torso of a patient with respect to the patient's legs are known. The inclined position assists breathing and allows the patient more freedom of movement to observe and to better interact with surrounding objects than in a flat, supine, position. One specialized use for a patient incline device is to place the head and neck of the patient in better position for an intubation procedure in which an endotracheal tube is inserted into the patient's airway. The desired position for the patient being intubated, in which the trachea is opened, is sometimes referred to as the “sniffing” position.
As discussed in U.S. Patent Publication No. 2005/0193496, it is also known to use incline devices to elevate the head of patients for whom laying in a supine condition for extended periods of time would be unhealthy. This is particularly true for morbidly obese patients because excess fat in the chest wall area compresses the lungs, making it more difficult for the patient to breath. Such respiratory difficulty can aggravate other conditions such as Chronic Obstructive Pulmonary Disease (COPD) and Congestive Heart Failure (CHF).
The work of breathing (“WOB”) includes an elastic component that is primarily influenced by the inward recoil of the lungs and the outward recoil of the chest wall. Elastic work during breathing is performed primarily during inspiration as the lungs and chest wall are expanded creating a pressure gradient to move gas into the lungs. Factors that contribute to the elastic WOB include the stiffness (i.e., a measure of compliance) of the pulmonary tissue, recoil pressure of the chest wall, and resistance offered by the abdominal cavity.
When respiratory excursion (i.e., the outward movement of the chest wall during inspiration) is impaired by morbid obesity, skeletal or pulmonary disease, pregnancy or severe burns to the chest wall, the intrathoracic volume is compressed and chest wall compliance is impaired. This dramatically increases the WOB that is required to maintain functional residual capacity and an adequate tidal volume and can result in ventilation-perfusion (V/Q) mismatch, lung collapse, and hypoventilation. Also, mask ventilation tends to be difficult because of low chest wall compliance, particularly for morbidly obese patients as a result of increased intra-abdominal pressure caused by large abdominal fat accumulations.
When a patient is inclined using a conventional incline device having a sloped incline ramp that contacts the head and upper torso of the patient, the spine of the patient may not be fully supported along its length such that an upper portion of the spine curves (i.e., analogously to a standing person exhibiting a crooked or “hunched” posture). Such curvature of the upper spine tends to contract the chest wall area of the patient. Thus, the respiratory benefits associated with inclining a patient, particularly an obese patient, are not fully realized because of undesirable misalignment of the spine. In addition, the condition of sleep apnea may be aggravated for patient's that are inclined for extended periods of time with the spine in an unsupported condition.